Category: Geography

Today, December 21, is the Winter Solstice, the Northern Hemisphere’s shortest day of the year. In the Southern Hemisphere, however, it was Summer Solstice, the longest day of the year.

What exactly is the Winter Solstice?

• The winter solstice, also known as the hibernal solstice, occurs when either pole of the Earth reaches its maximum tilt away from the Sun.
• This occurs twice per year, once in each hemisphere.

What are Solstices?

• Solstices occur because Earth’s axis of rotation is tilted about 23.4 degrees relative to the sun’s orbit.
• Our planet’s seasons are driven by this tilt, as the Northern and Southern Hemispheres receive unequal amounts of sunlight over the course of a year.
• The Northern Hemisphere is tilted more toward the sun from March to September, driving its spring and summer.
• The Northern Hemisphere is tilted away from the sun from September to March, making it feel like autumn and winter.
• The seasons in the Southern Hemisphere are flipped.
• The Earth’s axis is tilted most closely toward the sun at two points each year, known as solstices.

Impact on day-time

• The hemisphere with the greatest tilt toward our home star has the longest day, while the hemisphere with the greatest tilt away from the sun has the longest night.
• The Northern Hemisphere’s summer solstice—which always falls around June 21—is followed by the Southern Hemisphere’s winter solstice.
• Similarly, the Northern Hemisphere’s winter solstice—which always falls around December 22—is followed by the Southern Hemisphere’s summer solstice.

Impact of the tilted axis

• The Northern Hemisphere is tilted in the direction of the Sun for half of the year, receiving direct sunlight during long summer days.
• It tilts away from the Sun during the other half of the year, making the days shorter.
• On the Winter Solstice, December 21, the North Pole is most tilted away from the Sun.
• The tilt is also responsible for the various seasons that we experience on Earth.
• The side facing the Sun has day, which changes to night as the Earth spins on its axis.

Un-impacted regions

• Day and night are equal on the Equator. The more extreme the variation, the closer one gets to the poles.
• That pole is tilted towards the Sun during summer in either hemisphere, and the polar region receives 24 hours of daylight for months.
• Similarly, the region is completely dark for months during the winter.

In Vedic tradition

• The northern movement of the Earth on the celestial sphere is implicitly acknowledged in the Surya Siddhanta in Vedic tradition.
• It describes the Uttarayana (the period between Makar Sankranti and Karka Sankranti). As a result, the Winter Solstice is the first day of Uttarayana. 

• A study published in Nature Geoscience contends that at least some of the Earth’s early oxygen came from a tectonic source through the movement and destruction of the Earth’s crust.
• Subduction is a phenomena in which an oceanic plate slides beneath a continental plate.

Subduction

• Plate tectonics refers to the tectonic activity that currently dominates the Earth. The oceanic crust, the topmost layer of the Earth underneath the oceans, subducts, or sinks, into the Earth’s mantle.
• A continental plate collides with an oceanic plate and descends beneath it. The space between Earth’s crust and core is known as the mantle.
• At regions of convergence known as subduction zones, the oceanic crust dips into the Earth’s mantle. According to the report, there is substantial disagreement on whether plate tectonics existed throughout the Archean epoch, which accounts for one-third of Earth’s history.

The Archean Earth

• The Archean eon, which spans 2.5 billion to 4 billion years ago, accounts for one-third of the history of our world.

Features

• This alien Earth was a water world, with green oceans covering everything (Green Rust-an Iron Mineral)

Earth’s Iron ore deposits

• “Green rust” that formed in seawater and sank to the ocean floor millions of years ago is the origin of banded iron formations.
• The minerals we can currently see in the geologic record were created from the iron in the green rust.
• Its atmosphere was obscured by a methane haze, and there was no oxygen in the air. It may have indirectly contributed to the Great Oxidation Event, when oxygen began to build up in the atmosphere.
• There was no multicellular life at all.
• Prokaryotes, or simple single-celled organisms without nuclei, were the only living things.
• The nature of this world’s tectonic activity was another strange feature.

Creating oxygen from water

• According to the experiment, the magma’s sulphur level rose from 0 to 2000 parts per million over the course of 2705 million years.
• This suggested that the sulphur content of the magma had increased.
• Additionally, it was confirmed that the sulphur originated from an oxidised source that matched the information from the host zircon crystals.
• It suggests that oxidised magmas did originate 7 billion years ago, during the Neoarchean period.

New findings indicate

• The oxygen in these magmas must have come from another source and was ultimately released into the atmosphere during volcanic eruptions, as the development of sulfur-rich, oxidised magmas in the subduction zones was not prevented by the absence of dissolved oxygen in the Archean Ocean reservoirs.

Importance

• The study extends beyond the understanding of early Earth geodynamics, and it suggests that oxygenation of the Earth may have been greatly aided by archean subduction.
• Future research on life on other rocky planets and the lack of oxygen may be partially explained by the findings of this study.

@the-end

• The presence of magmas shows that subduction, which forces ocean water to travel hundreds of kilometres inside Earth, produces free oxygen, according to the paper. The result is oxidation of the mantle above.
• The study came to the conclusion that an unanticipated factor in the oxygenation of Earth may have been Archean subduction. The only planet where life could exist is Earth, which may be the only spot in the solar system with plate tectonics and active subduction.

Tropical Storm Gardo recently moved closer to Typhoon Hinnamnor and developed into a Super-Typhoon exhibiting the Fujiwhara effect.

The strongest tropical cyclone of the year, super typhoon Hinnamnor, was barreling towards Taiwan on September 1, 2022. As they approached one another, they began to dance around the central line between them, demonstrating a classic case of the Fujiwhara Effect.

Fujiwhara effect 

• Sakuhei Fujiwhara, a Japanese meteorologist who found contact between two cyclonic vortices while they were close to one another, is honoured with the name of this phenomenon.
• Sakuhei Fujiwhara, a Japanese meteorologist who published the first report identifying the Fujiwhara incidents in 1921, is credited with discovering the Fujiwhara effect.
• Typhoons Marie and Kathy merging in the western Pacific Ocean in 1964 was the first known instance of the effect.
• The Fujiwhara effect is any interaction between tropical storms that were formed at the same time in the same ocean region, with their centres or eyes at a distance of less than 1,400 km and intensity ranging from a depression to a super typhoon.
• It has an intensity that can range from a depression (wind speed less than 63 km/h) to a super typhoon (wind speed over 209 km per hour).
• An frenetic dance between two hurricanes rotating in the same direction starts when they are sufficiently close to one another.
• If one storm is significantly stronger than the other, the weaker hurricane will orbit it before colliding with its vortex and being consumed.

Different ways in which Fujiwhara Effect can take place:-

• The most frequent scenario is elastic interaction (EI), in which only the storms’ motion direction changes.
• These are also the cases that call for more in-depth investigation and are challenging to evaluate.
• Partial straining out (PSO), the second method, involves losing a portion of the smaller storm to the environment.
• The smaller storm is totally lost to the atmosphere in the third scenario, known as complete straining out (CSO), which does not occur for storms of comparable strength.
• The fifth type is complete merger (CM), which occurs when two storms of similar strength merge completely. The fourth type is partial merger (PM), in which the smaller storm merges into the bigger one.
• During a merger interaction between two tropical cyclones the wind circulations come together and form a sort of whirlpool of winds in the atmosphere.

• In order to provide irrigation for different crops, Odisha, which has seen seven cyclones in the last three years, has installed underground pipelines.
• In response to climate change, Odisha is considering crops that use less water.

Pipeline-based irrigation system

• It debuted in 2017.
• The pipeline-based irrigation system promotes crop diversity and effective water utilisation.
• With the state government’s emphasis on crop diversification, Odisha has finished more than 3.5 lakh hectares (lh) of such a system, and the total area under it is anticipated to expand to 4 lh. 

Pros

• Cross Drainage and Cross Masonry (Communication) constructions can be eliminated or minimised, and pipe systems are better equipped to fit current patterns of land ownership with the least amount of interruption.
• During the rainy season, irrigation projects obstruct free drainage of water, which causes standing crops and even villages to be flooded.
• More suitable solution for areas prone to flooding;
• No damage caused by excessive rain or flooding during the monsoon.
• The main goals of modernising irrigation schemes and digital management will be met when water is delivered through the piped irrigation network, as there will be no obstructions to farmers’ and farm equipment’s mobility.
• Chemicals and fertilisers may also be combined with water.
• Since the amount of water delivered by the piped irrigation network is simple to measure, water auditing can be done with accuracy.

Drawbacks

• Piped irrigation networks may not be appropriate if the irrigation water contains significant amounts of sediments, and their initial costs are often greater than those of canal distribution networks.
• In these circumstances, desilting arrangement would be required.

Application

• In areas where water is valuable both in terms of the crops that can be cultivated there and in terms of its limited supply, as shown by low reservoir capacity or stringent regulations on the withdrawal of water from groundwater or river sources.
• Where open canal seepage losses from poorly cohesive soils would be very high.
• When high ground levels prevent an open canal system from reaching irrigable land.

Odisha Millet Mission

• It is a flagship programme of the Government of Odisha’s Department of Agriculture and Farmers.
• The Odisha Millets Mission, a special programme for the promotion of millets in tribal areas of Odisha, was introduced in 2017.
• As part of the free meals served in schools, Odisha has introduced ragi in anganwadis and plans to do the same with millet.

Source—https://www.thehindubusinessline.com/economy/agri-business/odisha-adopts-underground-pipeline-based-irrigation-system-in-a-big-way/article66135425.ece

The most recent report from the UN, titled ‘UN World Population Prospect 2022’, was just made public.

• On November 15, 2022, the world’s population is expected to reach 8 billion, a milestone that denotes significant advancements in public health that have lowered mortality rates and raised life expectancy.
• Most of this expansion has been driven by Asia and Africa.
• By 2037, it is anticipated that they will provide the next billion, whilst Europe’s contribution would be negative due to a shrinking population.
• After the death rate started to decline, the population grew dramatically, reaching a peak of 2.1% year between 1962 and 1965.
• The global population increased from 2.5 billion to 5 billion people between 1950 and 1987.
• About 70% of the population growth from 7 to 8 billion people occurred in low- and lower-middle-income countries.
• The two most populous regions in the world in 2022 were both in Asia: Central and Southern Asia had 2.1 billion people and Eastern and South-Eastern Asia had 2.3 billion people, or 29% of the world’s population.
• Between now and 2050, the global increase in the population under the age 65 will occur entirely in low income and lower-middle-income countries, since population growth in high-income and upper-middle income countries will occur only among those aged 65 or more.
• With populations of over 1.4 billion apiece, China and India made up a bigger portion of the world’s population in 2022.
• In 2020, the world’s population decreased by less than 1%, rising at its sluggishest rate since 1950.
• Up from 40% in 1990, 60% of the world’s population now resides in areas where the fertility rate is below the replacement level.India, Pakistan, Nepal, Bangladesh, and Sri Lanka have all experienced significant emigration in recent years.

Forecasts for the report

• Around 8.5 billion people could live on the planet by 2030, 9.7 billion by 2050, and 10.4 billion by 2100.
• In 2050, India’s population is projected to reach 1.66 billion, surpassing China’s 1.37 billion.
• In 2022, persons in India between the ages of 15 and 64 made up 8% of the population, while those 65 and over made up 7%.
• By 2023, India will overtake China as the world’s most populous nation. By 2050, the population of eight countries—India, Nigeria, Ethiopia, Egypt, Congo, the United Republic of Tanzania, Pakistan, and the Philippines—will have increased by more than half of the projected rate.
• Between 2022 and 2050, it is predicted that the populations of 61 countries or regions would decline by 1% or more, as a result of persistently low fertility rates and, in some circumstances, high emigration rates.
• However, the 46 least developed nations are among those with the fastest growing economies.

Total Fertility Rate (TFR): India

• In India, the [population] replacement level of 2.1 has been reached in 31 states and union territories.
• The national TFR for India has decreased from 2.2 to 2.0.
• In states like Bihar, Meghalaya, Manipur, Uttar Pradesh, Jharkhand, and Madhya Pradesh, TFR is higher than the national average.
• An rise in the use of contemporary family planning techniques and a decrease in the unmet need for family planning are the main causes of the decline in fertility.

Current situation of India and way forward

• The proportion of people who were of working age peaked at 66% globally in 2012, however in India it stood at 70% in 2020. This demonstrates that India’s performance in comparison to the rest of the globe is lacking. Additionally, studies show that compared to other Asian nations, India has not reaped the same economic benefits from the demographic transformation.
• In addition, while the global average for the proportion of people in working age was 59%, India’s was 46% in 2021.
• When it comes to women’s employment in India, the situation is worse. According to figures from the World Bank, only 19% of women are employed globally, compared to 46% in India.
• As a result, India has to hire more women, develop the appropriate policies, and increase the quality of its human resource overall. India will be able to effectively use its demographic dividend thanks to this.